1. Field of the Invention
The present invention relates to a multilayer ceramic capacitor and a method for manufacturing the capacitor, and more particularly, to a multilayer ceramic capacitor including an external electrode with a multilayer structure, and a method for manufacturing the capacitor.
2. Description of the Related Art
In recent years, multilayer ceramic capacitors have come to be used even under severe environments which are more likely to have impacts on the capacitors than ever before, and thus have been required to have mechanical strength which can cope with environmental conditions. For example, multilayer ceramic capacitors for use in mobile devices such as cellular phones and portable music players are required to withstand drop impacts and the like. Specifically, there is a need for the multilayer ceramic capacitors to be kept from dropping from mounting boards and from being cracked, even when the capacitors are subjected to drop impacts and the like. In addition, multilayer ceramic capacitors for use in in-car devices such as ECUs are required to withstand impacts such as thermal cycles. Specifically, there is a need for the multilayer ceramic capacitors to be kept from being cracked, even when the capacitors are subjected to warping stress and tensile stress applied to external electrodes by linear expansion and shrinkage of mounting boards in thermal cycles.
For the purpose of meeting the demand described above, multilayer ceramic capacitors are known which include external electrodes including thermosetting resin layers. JP11-162771A discloses such a multilayer ceramic capacitor.
The multilayer ceramic capacitor in JP11-162771A includes external electrodes of multilayer structure, including electrode layers as baked electrodes provided on both end surfaces of a capacitor main body, and conductive thermosetting resin layers provided on the surfaces of the electrode layers. In the case of the multilayer ceramic capacitor in JP11-162771A, the electrode layers of the external electrodes of multilayer structure carry the function of ensuring moisture resistance reliability, whereas the thermosetting resin layers thereof carry the function of preventing the capacitor main body from being cracked.
In the case of the multilayer ceramic capacitor as described in JP11-162771A, the thermosetting resin layer includes a resin, thus lowering the content ratio of the metal contained in the thermosetting resin layer. Therefore, the adhesion force has a tendency to be weak between the thermosetting resin layer and the electrode layer provided on the lower surface of the thermosetting resin layer. Thus, the multilayer ceramic capacitor as described in JP11-162771A has the problem of causing ingress of water and the like between the thermosetting resin layer and the electrode layer, thus degrading moisture resistance reliability and electrical characteristics.